1. Field of the Invention
The present invention relates to a transmission used for automobiles, agricultural machinery, construction machinery, and industrial machinery, among some others. More particularly, the invention relates to the ratchet one-way clutch that uses ratchet (pawl member) for a lock mechanism, among the one-way clutches used for an automatic transmission or the like adopted for vehicles to carry out the function of back stop or the like. More specifically, the invention relates to a ratchet one-way clutch provided with means for reducing the dragging torque of bearing.
2. Related Background Art
In general, the one-way clutch used for the automatic transmission is provided with the outer race and inner race that rotate relatively, and arranged to transmit the rotational torque only in one direction by allowing the sprag, roller, and others, which transmit the torque between the outer and inner races, to engage with the surface of a cam provided for the raceway surface of the outer race or the inner race. Also, the structure is arranged so that the clutch makes idle rotation in the reverse direction.
Of the one-way clutches thus arranged, there is the ratchet one-way clutch that uses the ratchet as a torque transmission member that transmits torque between the outer and inner races. The ratchet one-way clutch comprises the outer race with pockets on the inner circumference thereof; the inner race with notches on the outer circumference thereof arranged coaxially with the outer race; the pawl member that transmits torque between the inner and outer races in a state of being engaged with each notch of the inner race housed in the pocket so as to lock the one-way clutch; and the elastic member such as a spring that biases the pawl member to the inner race.
The pawl member of the ratchet one-way clutch thus structured is made slidable freely on the outer circumference of the inner race when the one-way clutch rotates in one direction, thus enabling the outer race and inner race to relatively rotate idly. Then, when the one-way clutch begins to rotate in the other direction, the pawl member engages with the notch so that the one-way clutch is conditioned to be locked up.
FIG. 3 and FIG. 4 are views which illustrate one example of the conventional ratchet one-way clutch which is used for the stator of a torque converter. FIG. 3 is a sectional view on the front side, which shows the conventional ratchet one-way clutch. FIG. 4 is a sectional view taken in the axial direction in FIG. 3. The torque converter 51 comprises a runner 54 having the outer race portion 53 on the inner circumference; the inner race 52 which is arranged coaxially with the outer race portion 53 with the recessed portion 71 on the outer circumference; the pawl member 60 which is arranged for each of the pockets 65 provided on the inner circumference of the outer race portion 53 to transmit torque by being fitted into the recessed portion 71; the biasing member 61 which is installed on the hollow portion 66 provided for the pocket 65 to bias the pawl member 60 in the direction of the inner diameter; the bush 56 which supports the pawl member 60 and biasing member 61 in the axial direction and slidably moved on the inner race 52; and a snap spring 57 for preventing the bush 56 from falling off. For the biasing member 61, a corrugated spring is mainly used.
In this respect, each of recessed portions is arranged per designated pitch for the ratchet one-way clutch thus structured, and fitting is made after a slight idle rotation in the engaging direction. As a result, the torque which is loaded at the time of fitting becomes excessive instantaneously. Thus, there is a fear that hammering sounds are generated. Also, shocks are repeated at the time of fitting, which may result in making the life of the ratchet one-way clutch shorter.
It is an object of the present invention to provide a ratchet one-way clutch having a shock absorbing mechanism incorporated therein to absorb shocks at the time of fitting, being capable of preventing hammering sounds, while improving the life thereof.
In order to achieve the object described above, the ratchet one-way clutch of the present invention comprises an inner race provided with recessed portions on the outer circumference; an outer race member arranged coaxially with the inner race, being provided with pockets on the inner circumferential side; a pawl member arranged for each of the pockets to transmit torque by being fitted into each of the recessed portions; and a biasing member for biasing the pawl member in the inner diametral direction to promote the fitting. For this clutch, an operating element is provided to relatively rotate with respect to the outer race member, and an elastic member resides inclusively between the outer race member and the operating element.
Also, for the ratchet one-way clutch of the invention, extrusions are provided for the outer race member and the operating element, each of which is extended in the diametral direction, and when the end faces of the extrusions in the circumferential direction abut against each other, the range of the relative rotation is restricted.
Further, for the ratchet one-way clutch of the invention, the outer race member is provided with an extended portion that extends inwardly in the diametral direction, and then, the extended portion supports the pawl member and the biasing member in the axial, direction, while slidably moving with respect to the inner race.
For the present invention, the example, in which the ratchet one-way clutch is used for the stator of an automatic transmission, is shown as in the case of the prior art. With the provision of an operating element that relatively rotates with respect to the outer race member, an elastic member is arranged to reside inclusively between the outer race member and the operating element to make it a shock absorbing mechanism.
For the present embodiment, the portion of the runner on the inner circumferential side is made an operating element, and a coil spring is used as the elastic member. Also, the outer race member is structured with the outer race shown in the conventional example which is formed integrally with a bush.